Display Average in an SQL query

Question

I want to conduct a search in a query So far I have only been able to display the total value of the records. the idea is to show the spending average. Then it would be the (total / quantity) however I could not mount the logic: what I have so far presented the Count of all records

with AdoMEdOs do
begin
   Close;
   Sql.clear;
   AdoMEdOs.SQL.Add('select valor_total from ordem_servico');
   open;
   RecordCount;
   label5.Caption := IntToStr(AdoMEdOs.RecordCount) ;
   AdoMEdOs.Close;
end;

Answer 1

This can be done using SQL or in the application. I recommend it by SQL as it is simpler and more effective (since the data is in the database). If this is done by SQL, then the aggregator function called avg, thus:

select avg(valor_total) as media from ordem_servico